President Bush's State of the Union claim - now discredited - that Iraq tried to purchase nuclear materials from Africa was only one item in a long list of charges making the case for war. But it has sparked one of the biggest political firestorms of Mr. Bush's tenure - which, despite the administration's strenuous efforts to quell it, shows little sign of fading away.

Although CIA director George Tenet has taken responsibility for failing to excise the charge from the president's address, a number of questions remain unanswered, such as why the information was included in the first place, given that Mr. Tenet reportedly had struck a similar line from a presidential speech three months earlier.

Democrats are attacking the president's reliance on flawed evidence - and his subsequent efforts to shift the blame elsewhere - to try to undercut his image as a straight shooter, one of his greatest political strengths. But even if the public largely accepts that the president simply made an honest mistake, the incident may feed an already growing belief that the administration, whether intentionally or not, overestimated the Iraqi weapons threat in the run up to war. Particularly as the instability in Iraq continues, with more and more US troops losing their lives and no weapons of mass destruction yet found, more Americans may begin to question whether the war was worth it - and whether the president led the nation on an appropriate course.

"If it becomes more vivid in people's minds that there was not a serious threat [in Iraq], then the costs will become even more salient, and people may feel we made a mistake" in going to war, says Steven Kull, director of the Project on International Policy Attitudes. "We're not there yet," he adds. "But the arrows are going in that direction."

The White House argues that the State of the Union claim is being blown out of proportion: "We're talking about one line, one data point," National Security Adviser Condoleezza Rice said on CBS's Face the Nation Sunday. The larger point remains, she says, that the US had longstanding evidence of Saddam Hussein's weapons capability, and that it has now removed a significant threat from a volatile region with ties to terrorism. In the wake of Sept. 11, if Bush had ignored the threat posed by Mr. Hussein, "he would not have been doing his duty," Ms. Rice said.

Democrats sharpen attacks

Still, Democrats are seizing on the false claim, along with the broader problems US troops are having in postwar Iraq, to raise questions about both the administration's credibility and its competence. And while the Democratic Party was sharply split over the Iraq war in the run-up to the conflict, it has been far more unified on the issue in recent days. Pro-war presidential candidates such as Sens. John Kerry and Joseph Lieberman have attacked the administration's handling of the postwar phase and its overall use of intelligence. Meanwhile, former Vermont Gov. Howard Dean, one of the strongest opponents to the Iraq war, placed a petition on his website calling for an investigation into the Bush's justification for the invasion.

The administration's failure to find any weapons of mass destruction leads to two inescapable conclusions, Democrats say: That the weapons never existed in the first place, or that the US somehow failed to prevent them from being disseminated in the aftermath of the war.

"They can either say that they were dishonest or that they were incompetent," says an adviser to one Democratic presidential candidate. "Did they not have a plan to secure the weapons of mass destruction? Is that possible?"

So far, much of the controversy has been confined to the Beltway: When a Newsweek survey recently asked voters for their reaction to Bush's discredited assertion that Iraq tried to acquire uranium from Africa, 72 percent said they knew nothing about it.

Still, there are signs the public is now having second thoughts about the Bush administration's representation of the Iraqi weapons threat. According to a CBS poll, while only 11 percent of Americans believe the White House actually lied about Iraq's weapons of mass destruction, 45 percent think the administration was hiding important elements of what it knew. Likewise, Americans are now evenly divided on whether the end results of the war have been worth the costs.

"What props [Bush] up is the war on terrorism, winning the war in Iraq - and the fact that Americans like him," says independent pollster John Zogby. Now, many things are chipping away at that support, from the flat economy, to the instability in Iraq, to the mounting number of US casualties. "If you add to that the final Vietnam War equation - which is government misrepresentation or lying - that can be very troublesome," he says.

Reagan's precedent

Historians note that the original "Teflon" president, Ronald Reagan, saw his public support erode substantially when his credibility was questioned during the Iran-contra affair.

"Iran-contra did great damage to Ronald Reagan," says Douglas Brinkley, a historian at the Eisenhower Center for American Studies. "If he had had to run for reelection again, it would have caused real problems."